Strip (which may also be referred to herein as “sheet”) materials are used or produced in various industries. In at least certain of these industries, it is desired that a strip of material of interest have as flat a profile as possible. Unfortunately, it is also known that at least certain strip material manufacturing processes commonly impart one or more types of deformation to the strip materials produced thereby, which deformation tends to reduce the flatness of the strip materials. To that end, various devices, systems and techniques have been developed for both detecting and correcting the flatness of a moving strip of material.
While not limited thereto, a common use of such aforementioned flatness detecting and correcting devices, systems and techniques occurs in the production of strip metal products, wherein hot slabs or billets of steel and other metals are rolled into thin sheets. This hot-rolling process, as well as several devices, systems and techniques for detecting and/or correcting the flatness of sheet metal products produced thereby, is described in more detail in U.S. Pat. No. 6,587,301 (the '301 patent) to Bergman et al.
As described in the '301 patent, hot-rolling mills typically produce sheet metals by using a series of rolls to exert a pressing force on a hot slab or billet that is passed beneath the rolls. However, exertion of a uniform pressing (flattening) force across the width of the strip is difficult. Consequently, finished strip materials often possess undesirable shape defects, such as a wavy edge(s) or a center buckle. These shape defects are generally the result of a non-uniform lengthwise stretching of the strip across its width. This non-uniform stretching produces stresses within the strip that lead to shape defects such as those recited above.
As also described in the '301 patent, microprocessor-controlled multi-roll levelers capable of automatically correcting for such shape defects in metal strip materials now exist and are available from Machine Concepts, Inc. in Minster, Ohio. Shape defects in the strip materials may be detected and provided to these levelers by shape measurement devices. To this end, both an air-bearing shape meter and displacement-type shape sensor are described in the '301 patent for detecting shape defects in moving strips of metal and other materials. Basically, an air-bearing shape meter operates to detect shape defects by sensing changes in the contact forces imparted thereto by a passing strip of material. In contrast, a displacement-type shape sensor, which is of interest here, operates to detect shape defects by measuring an amount of linear displacement of a sensor(s) thereof afforded by a loose section of a strip of material passing overhead.
In addition to the air-bearing shape meter and displacement-type shape sensor described above, both of which make contact with the material being examined, a novel non-contact type shape sensor device has also been developed and is also available from Machine Concepts, Inc. Examples of this non-contact shape sensor are described in more detail in U.S. Pat. No. 7,918,124 (the '124 patent) to Eiting et al. Generally speaking, and without limiting the scope of the '124 patent, a non-contact shape sensor device of the '124 patent is a displacement-type shape sensor device employing a number of fluid-emitting sensor heads that allow a moving strip of material passing by the sensor heads to float on a cushion of fluid instead of directly contacting the sensor heads. Both a contacting and non-contact displacement-type shape sensor device may comprise a number of individual shape sensors arranged to traverse the width of a moving strip of material.
While both of the displacement-type shape sensors described respectively in the '301 patent and the '124 patent work quite well, it is nonetheless realized that there exist certain conditions wherein operation of a displacement-type shape sensor may be further optimized. Particularly, normal practice is to retract (deactivate) any sensors that are completely outside of the width of a strip of material being examined, as well as any sensors that will be only partially covered (to some predetermined extent) by the strip of material being examined. In other words, it is preferable that the edges of the strip be as close as possible to the outside edges of the outside-most active shape sensors.
In the case of a displacement-type shape sensor employing a series of roller bearings, such as is described in the '301 patent, deactivation of the sensor(s) ensures that neither the sensor or the edge of the strip of material will be damaged as the strip of material moves across the shape sensor device. In the case of a shape sensor employing a fluid-emitting sensor head, as described in the '124 patent, deactivation of the sensor(s) may be appropriate when the edges of the moving strip of material cover an insufficient number of the sensor head fluid-emitting nozzles to allow for proper operation of the sensor. Consequently, a controller in communication with such a shape sensor device is typically programmed to deactivate the outside-most sensors when the location of the edges of a given strip on the outside-most sensors (with respect to the width of that strip) is not sufficiently close to the outside edge of the roller or sensor head. The distance from the outside roller/sensor head edge that results in deactivation of the sensors may vary.
One problem associated with deactivating partially contacted/covered outside sensors as described above, is that the strip of material may then overhang by a significant amount the sensors that subsequently become the outside-most active sensors. Without a sensor under the edges of the overhanging section of the strip, there may be insufficient edge shape information to feed back to the control system of a leveler, other shape correction apparatus, etc. Consequently, defects located along the edge portions of the strip of material may not be adequately detected and said defects may not be acceptably corrected.
It can be understood from the foregoing comments that there is room for optimization of displacement-type shape sensor devices and their methods of use for detecting defects in the shape of a moving strip of material. Embodiments of devices, systems and methods of the invention are so optimized.